Simplified the node to only advertise a single service - a query allows other nodes to find out, simply, the total distance traveled. The node also only handles plain encoder ticks, because distance and such computation should be done on the library end.

This is a broken commit because I decided to do this at a bad time. Sorry! The build will be working after next commit, I promise (and I won't push till then). This commit reflects the licensing in the files after I used my auto-add/remove script.

Updated encoder node code with preliminary driver functionality.Renamed encoder_state.msg to encoders_state.msg.Added functions to encoders.cpp to send message of current encoder state.Added function headers to encoders.h.Added function to encoders.cpp to convert to different units....